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nullb: support discard

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discard makes sense for memory backed disk. And also it's useful to test
if upper layer supports dicard correctly.

User configures 'discard' attribute to enable/disable dicard support.

Based on original patch from Kyungchan Koh

Signed-off-by: Kyungchan Koh <kkc6196@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Shaohua Li 2017-08-14 15:04:57 -07:00 committed by Jens Axboe
parent 5bcd0e0c79
commit 306eb6b4ad
1 changed files with 41 additions and 1 deletions
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42
drivers/block/null_blk.c
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@ -88,6 +88,7 @@ struct nullb_device {
bool use_per_node_hctx; /* use per-node allocation for hardware context */
bool power; /* power on/off the device */
bool memory_backed; /* if data is stored in memory */
bool discard; /* if support discard */
};
struct nullb {
@ -318,6 +319,7 @@ NULLB_DEVICE_ATTR(use_lightnvm, bool);
NULLB_DEVICE_ATTR(blocking, bool);
NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
NULLB_DEVICE_ATTR(memory_backed, bool);
NULLB_DEVICE_ATTR(discard, bool);
static ssize_t nullb_device_power_show(struct config_item *item, char *page)
{
@ -373,6 +375,7 @@ static struct configfs_attribute *nullb_device_attrs[] = {
&nullb_device_attr_use_per_node_hctx,
&nullb_device_attr_power,
&nullb_device_attr_memory_backed,
&nullb_device_attr_discard,
NULL,
};
@ -425,7 +428,7 @@ nullb_group_drop_item(struct config_group *group, struct config_item *item)
static ssize_t memb_group_features_show(struct config_item *item, char *page)
{
return snprintf(page, PAGE_SIZE, "memory_backed\n");
return snprintf(page, PAGE_SIZE, "memory_backed,discard\n");
}
CONFIGFS_ATTR_RO(memb_group_, features);
@ -815,6 +818,20 @@ next:
return 0;
}
static void null_handle_discard(struct nullb *nullb, sector_t sector, size_t n)
{
size_t temp;
spin_lock_irq(&nullb->lock);
while (n > 0) {
temp = min_t(size_t, n, nullb->dev->blocksize);
null_free_sector(nullb, sector);
sector += temp >> SECTOR_SHIFT;
n -= temp;
}
spin_unlock_irq(&nullb->lock);
}
static int null_transfer(struct nullb *nullb, struct page *page,
unsigned int len, unsigned int off, bool is_write, sector_t sector)
{
@ -843,6 +860,11 @@ static int null_handle_rq(struct nullb_cmd *cmd)
sector = blk_rq_pos(rq);
if (req_op(rq) == REQ_OP_DISCARD) {
null_handle_discard(nullb, sector, blk_rq_bytes(rq));
return 0;
}
spin_lock_irq(&nullb->lock);
rq_for_each_segment(bvec, rq, iter) {
len = bvec.bv_len;
@ -871,6 +893,12 @@ static int null_handle_bio(struct nullb_cmd *cmd)
sector = bio->bi_iter.bi_sector;
if (bio_op(bio) == REQ_OP_DISCARD) {
null_handle_discard(nullb, sector,
bio_sectors(bio) << SECTOR_SHIFT);
return 0;
}
spin_lock_irq(&nullb->lock);
bio_for_each_segment(bvec, bio, iter) {
len = bvec.bv_len;
@ -1207,6 +1235,16 @@ static void null_del_dev(struct nullb *nullb)
dev->nullb = NULL;
}
static void null_config_discard(struct nullb *nullb)
{
if (nullb->dev->discard == false)
return;
nullb->q->limits.discard_granularity = nullb->dev->blocksize;
nullb->q->limits.discard_alignment = nullb->dev->blocksize;
blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, nullb->q);
}
static int null_open(struct block_device *bdev, fmode_t mode)
{
return 0;
@ -1448,6 +1486,8 @@ static int null_add_dev(struct nullb_device *dev)
blk_queue_logical_block_size(nullb->q, dev->blocksize);
blk_queue_physical_block_size(nullb->q, dev->blocksize);
null_config_discard(nullb);
sprintf(nullb->disk_name, "nullb%d", nullb->index);
if (dev->use_lightnvm)